This invention relates to the investment casting process also known as the lost wax process. More particularly, the present invention relates to the employment of a paper receptacle to facilitate said process by functioning as both a vacuum enhancement liner and splash guard. The primary application of the instant invention is to facilitate said process in vacuum investment casting machines and investing machines in contradistinction to other types of utilitarian machines utilized in said casting, such as centrifugal or sand casting. Accordingly, any liners or guards used to facilitate investment casting by means other than vacuum casting machines have no bearing on the design of the instant invention.
The instant invention employs a single piece of fabricated paper of special design which serves as both a vacuum liner and splash guard in the investment casting flasks utilized in the vacuum casting machines. As a liner; the instant invention results in better castings due to a strong draw on the metal being cast into the flask and lower casting temperatures that has theretofore been possible; as well as a reduction in casting processing time. As a splash guard; the instant invention prevents the accumulation of investment slurry on metal flask surfaces and on the investing machine resulting in decreased cleanup costs, eliminating associate time losses resulting in cleanup, as well as enabling more lost wax modules to be placed in the same attendant space than has been heretofore allowed.
Now the use of paper to facilitate investment casting is not new. U.S. Pat. No. 1,119,373; issued Dec. 1, 1914, by Elza Stealy describes using a round disk of paper in the investment process which is consumed. U.S. Pat. Nos. 3,443,627 and 3,520,349 awarded to Claude H. Watts respectively, in 1969 and 1970, describes the construction of cardboard sprues to attach modules of wax to aid investment casting. This is not a vacuum liner or splash guard, nor is it utilized in vacuum investment casting. Subsequently, Kai was awarded U.S. Pat. No. 4,825,934 of May 2, 1989. It describes a paper cushioning sheet for exclusive use in denture casting to prevent special dental investment from cracking. While said sheet's appearance is similar in some respects to the instant invention, its function is not claimed to facilitate vacuum casting; and will not work in a vacuum casting machine.